1. Field of the Invention
This invention relates to fluid seals and in particular to an assembly wherein face seals are protected from pressure surges by a supplemental seal while being lubricated and cooled from a low pressure lubricant source.
2. Description of the Prior Art
In copending U.S. Letters Patent application Ser. No. 524,115, of Lawrence F. Schexnayder, for a Sealing Arrangement for Brake Housing, which is owned by the assignee hereof, an improved sealing structure is disclosed utilizing face seals and means for effectively preventing high pressure fluid conditions from adversely affecting the operation and life of the face seals. In the Schexnayder sealing structure, a buffer seal is provided for defining a flow restriction means to regulate the pressure of the coolant fluid delivered from the brake means therethrough to the face seals.
As disclosed in said application, the improved sealing structure thereof comprises an improvement over the prior structures of U.S. Pat. Nos. 3,180,648, of Bernard F. Kupfert et al, U.S. Pat. No. 3,072,220, of Elmer R. Bernson et al, and U.S. Pat. No. 3,136,389, of Curtis F. Cummins, each of which patents is owned by the assignee hereof. As disclosed in the Schexnayder application, the Kupfert et al patent discloses an improved ring-type face seal for sealing confronting surfaces of relatively rotatable parts. Lubricant is introduced under pressure into the apparatus and the seals are adapted to provide improved fluid sealing against such pressure.
In the Bernson et al and Cummins patents, these seals are used in conjunction with oil-cooled disc brakes.
As further pointed out in the Schexnayder application, a number of prior devices have been developed for balancing pressures in fluid-control devices. Illustratively, in Floyd S. Dadds et al U.S. Pat. No. 3,679,216, owned by the assignee hereof, a pressure-balanced track roller for underwater use is disclosed having piston or diaphragm means for maintaining face loads on the seal rings when the track roller is operated at substantial depths.
Additionally, Archibald S. Telfer U.S. Pat. No. 1,474,454 and 1,737,870, show a centrifugal pump utilizing pressure-balancing means; Kenton D. McMahan et al U.S. Pat. No. 2,575,923 shows a method and apparatus for pumping volatile liquids utilizing pressure-balancing means; and Robert W. Erikson et al U.S Pat. No. 2,931,314 shows an air purging apparatus for pumps permitting purging of the air to atmosphere and rapid closure of the pressure responsive valve on pump shutdown.